Using a Phillips screwdriver, unscrew the two screws securing the housing of the starting device..
... and remove the body and traction.
Remove the rubber sealing ring.
By pressing the diaphragm rod, close the inlet with your finger.
For a working starting device, the stem will return to its original position only after opening the hole.
If that doesn't happen, then...
... use a Phillips screwdriver to unscrew the three screws..
... and, having disassembled the case of the starting device, we change the faulty gasket or diaphragm.
We assemble the carburetor body cover in the reverse order of disassembly. We adjust the fuel level and the amount of ajar opening of the air damper (see Carburetor adjustment).